Many types of displays are commercially available in a variety of sizes and resolutions. These known types of displays include flat-panel displays (FPDs), such as liquid crystal displays (LCDs), plasma displays and organic light-emitting diode (OLED) displays, and non-FPDs, such as cathode ray tube (CRT) displays and projection displays.
While many applications are well served by these existing displays, there are other applications with size and resolution requirements that are not met by any single display. Such higher-end applications are likely to become more common due to the convergence of a variety of computational and information technologies that are creating an increasing need for larger, higher-resolution displays which are capable of effectively displaying large amounts of information. Unfortunately, various factors make it impractical to simply adapt existing display technologies to meet the needs of such higher-end display applications. For example, the size and resolution of LCDs are both limited by manufacturing and yield issues, and by the need to provide control signals to each pixel within the LCD. Because of the limits on the size and resolution of existing displays, the ability to design larger and higher-resolution displays to effectively present large amounts of information is limited.
Attempts have been made to produce larger and higher-resolution displays by combining smaller display tiles together to form tiled display systems. For example, one known type of tiled display system is constructed by physically joining an array of FPD tiles together, with adjacent FPD tiles placed into close physical abutment. Such systems, however, tend to contain visually disturbing seams between the tiles resulting from the gaps between adjacent pixels on adjacent tiles, and from any components (e.g., interconnects, adhesives, seals, mechanical alignment components, etc.) located between adjacent tiles.
Another known type of tiled display system includes multiple FPD tiles which are tiled together via projection. In such systems, a single projection lens is placed in front of each FPD tile to project the displayed image onto a screen, and the projected images from the multiple FPD tiles are merged together to form a single tiled image. Such systems, unfortunately, suffer from several problems. One problem is that the depth or thickness of such systems may be relatively large due to the limited practical field of view of the single projection lens, which requires that the distance from the lens to its associated FPD tile be proportional to the size of that FPD tile. If, for example, each FPD tile comprises an LCD having 1280×1024 pixels in a 338×270 mm viewing area (i.e., 3.8 dots/mm), the distance of the single projection lens from the LCD must be proportional to the relatively large size of the LCD, which will hamper efforts to make the system thin. Another problem is that the projection lens may require high-quality optical characteristics to meet minimal system resolution and distortion requirements, which is expensive. If, for example, each FPD tile comprises an LCD having 1280×1024 pixels, the single projection lens may have no more than 0.06% distortion to ensure that the error is kept within half of a pixel in the corner.
Thus, there is a need for a display system that is suitable for the larger size, higher-resolution requirements of many new applications. There is also a need for a tiled display system which does not include visually disturbing seams between the tiles. Further, there is a need for a tiled display system which merges together projected images from multiple tiles to form a tiled image, but which does not require high-quality (and expensive) optics. Also, there is a need for a projection tiled display system which has minimal depth. In addition, there is a need for a modular and scalable high-definition display system. Further, there is a need for a high-resolution display system which is low cost and easy to fabricate.